HBASE-12882 Log level now configurable from outside Log4j configuration

conf/log4j.properties

@@ -19,6 +19,7 @@ hbase.root.logger=INFO,console
 hbase.security.logger=INFO,console
 hbase.log.dir=.
 hbase.log.file=hbase.log
+hbase.log.level=INFO
 
 # Define the root logger to the system property "hbase.root.logger".
 log4j.rootLogger=${hbase.root.logger}
@@ -92,13 +93,13 @@ log4j.appender.asyncconsole.target=System.err
 
 # Custom Logging levels
 
-log4j.logger.org.apache.zookeeper=INFO
+log4j.logger.org.apache.zookeeper=${hbase.log.level}
 #log4j.logger.org.apache.hadoop.fs.FSNamesystem=DEBUG
-log4j.logger.org.apache.hadoop.hbase=INFO
-log4j.logger.org.apache.hadoop.hbase.META=INFO
+log4j.logger.org.apache.hadoop.hbase=${hbase.log.level}
+log4j.logger.org.apache.hadoop.hbase.META=${hbase.log.level}
 # Make these two classes INFO-level. Make them DEBUG to see more zk debug.
-log4j.logger.org.apache.hadoop.hbase.zookeeper.ZKUtil=INFO
-log4j.logger.org.apache.hadoop.hbase.zookeeper.ZKWatcher=INFO
+log4j.logger.org.apache.hadoop.hbase.zookeeper.ZKUtil=${hbase.log.level}
+log4j.logger.org.apache.hadoop.hbase.zookeeper.ZKWatcher=${hbase.log.level}
 #log4j.logger.org.apache.hadoop.dfs=DEBUG
 # Set this class to log INFO only otherwise its OTT
 # Enable this to get detailed connection error/retry logging.